جستجوی مقالات مرتبط با کلیدواژه "chitosan" در نشریات گروه "مواد و متالورژی"

In the present study, a design for the construction of poly-caprolactone (PCL)/gelatin (GEL)/chitosan (CS) scaffolds has been proposed in order to increase performance in tissue engineering. The artificial polymer PCL is used to increase the mechanical properties of the scaffold, and two natural polymers GEL and CS are used as factors in the proliferation of cells. Polycaprolactone-gelatin-chitosan ternary composites with different weight ratios of polycaprolactone (70, 80, 90 and 60) were made by double-sided electrospinning method. The samples were cross-linked in glutaraldehyde vapor with 25% by weight. Microscopic evaluation indicates the proper formation of the composite. FTIR analysis confirmed the bonding between the components in the composite samples. Also, the results of the water contact angle test showed promotion the hydrophilicity of the PCL scaffold by adding gelatin and chitosan. So that the contact angle of pure PCL reaches from 98 degrees to about 22 degrees with the presence of gelatin and chitosan. The evaluation of degradability in phosphate buffered saline solution showed that the weight loss of the fabricated scaffolds occurs with the passage of time from 1 to 28 days for all scaffolds. Because of the nature of poly-caprolactone and gelatin-chitosan, the highest degradation rate after 28 days in gelatin-chitosan fibers is more than 50% and the lowest degradation rate related to the sample containing 70 wt% PCL is less than 23%.

This research aimed to investigate the effect of nanoclay composite stabilized on chitosan surface in removing zinc, copper, iron and aluminum metals from fish meal Company effluent in 2017. Chitosan was prepared from common carp (Cyprinus carpio) skin. The amount of absorption of zinc, copper, iron and aluminum metals by chitosan-clay nanocomposite was investigated in five concentrations of 0, 0.2, 0.5, 0.8 and 1 weight percentage and at contact times of 60, 120 and 180 minutes. . In two concentrations of 0.2% and 0.5% of adsorbent and in contact times of 60 and 120 minutes, zinc and aluminum metals had the highest absorption rate compared to copper and iron metals, and in contact time of 180 minutes, iron metal had the highest absorption percentage (P<0.05). In concentrations of 0.8% and 1% of adsorbent in all three times, zinc metal has the highest removal percentage and aluminum has the lowest removal percentage (P<0.05) and two metals iron and copper rank second without any significant difference were placed (P<0.05). The results of the present study showed that the amount of metal absorption by chitosan-clay nanocomposite is related to the concentration of the adsorbent and the contact time and chitosan-clay nanocomposite can be used to remove and reduce the level of heavy metal contamination in the wastewater of fishmeal and other food factories.

Magnetic cobalt ferrite nanoparticles have been widely employed in various applications, such as medical applications due to their desirable characteristics. Although generally magnetic nanoparticles are appropriate for such employments, their applications are restricted due to their toxic properties. Hence, it is tried to decrease the toxic damages by using a biocompatible coating layer. For this purpose, in the present study, it was tried to synthesize Ca2+ and Gd3+ doped cobalt ferrite nanoparticles by the sol-gel auto-combustion method and coat them with chitosan and polyethylene glycol polymers. X-ray diffraction (XRD) pattern along with the Rietveld refinement results confirmed the formation of pure cobalt ferrite nanoparticles with the average crystallite size of 27 nm. Moreover, the results of both thermogravimetry (TGA) test and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of a coated layer of chitosan and polyethylene glycol polymers on the surface of nanoparticles. Magnetic characterization of the synthesized nanoparticles indicated that the formation of the coating layer can affect the magnetic properties, so that the saturation magnetization (Ms) increased from 67.93 to 74.61 emu/g. However, the coercivity (Hc) decreased from 982.86 to 908.13 Oe as a result of the formation of the coating layer.

Use of γ-glycidoxypropyltrimethoxysilane (GPTMS) enhances the stability and strength of hydrogels and improves the bioactivity and cellular performance of the scaffolds in bone applications. Given that one of the leading factors that affects the properties of the scaffold is the percentage of the cross-linking agent, chitosan and gelatin scaffolds with different percentages of GPTMS were prepared and evaluated through freeze-drying method. The results from Scanning Electron Microscope (SEM) confirmed the achievement of porous scaffolds with open pores and upon increasing the amount of cross-linking agent, the size of the pores reached approximately 290 microns. The results of the infrared spectrum showed the interaction among the polymers and process of cross-linking with the formation of silane groups. In this study, upon increasing the amount of the transverse bonding agent, the contact angle decreased, the optimal contact angle of the sample with 75 (weight percent) GPTMS reached 60.7 ± 3.5 degrees, and the percentages of both swelling and degradation ultimately decreased. It should be noted that the mechanical properties were improved by adding GPTMS up to 1590 ± 267 kPa. According to the findings of this study, application of GPTMS led to an enhancement in the bioactivity properties and deposition of the hydroxyapatite layer, and the X-ray diffraction pattern confirmed this claim. The obtained results support the hypothesis that gelatin-chitosan scaffolds with 75 (wt %) GPTMS seem to be the best samples for use in bone tissue engineering.

Skin, as the largest and one of the most vital organs of the human body, which is subject to damage more than other tissues, consists of three main layers: epidermis, dermis, and hypodermis. Tissue engineering and biomaterials as cell support can be used to regenerate the damaged parts of skin. In the present study, a three-layer scaffold was made for biomimicking the native skin tissue and accelerating wound healing. Poly(ε-caprolactone)/zinc oxide nanoparticles as porous polymer nanocomposite containing 0, 5, 10 and 15 wt.% zinc oxide nanoparticles prepared in two layers using solvent casting/salt leaching method. The third layer of chitosan as the external membrane was added by sodium hydroxide cross-linking agent on the previous two layers. The phase structure, chemical functional group, and morphology of the prepared scaffolds were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), respectively. To evaluate the mechanical properties, the prepared scaffolds were subjected to compressive strength test. The obtained results showed that the porosity of the three-layered scaffolds was partially changed in a gradient behavior. The structural integrity, morphological cohesion, and compressive strength of the scaffolds with 5 wt.% zinc oxide nanoparticles in which the cross-linking agent was used to add the chitosan membrane were significantly higher than the other prepared scaffolds.

The primary objective of the current research is to produce polymeric nanofibers of chitosan and polyvinyl alcohol containing chicory plant extract and then evaluate their antibacterial effects. As remarked by numerous published articles, the chicory plant proved to be able to modulate the activity and growth of bacteria. For this reason, chicory plant extract was added to the fiber precursor in the amounts of 1, 2, and 3 %. Finally, the morphology and antibacterial properties of the resultant nanofibers were investigated. The results from Field Emission Scanning Electron Microscope (FESEM) confirmed the formation of uniform fibers whose diameters decreased from 144 nm to 95 nm with an increase in the amount of the extract in the sample. In addition, Energy Dispersive X-ray (EDX) and X-map analyses confirmed the presence of elements of carbon, oxygen, nitrogen, chlorine, potassium, sodium, and copper in the precursor of the fibers containing the extract and their uniform distribution. In this study, Fourier Transform Infrared Spectroscopy (FT-IR) helped identify the functional groups and chemical bonds in the synthesized nanofibers. According to the Ultraviolet-Visible thermometry (UV-VIS) results, one emission in the ultraviolet region with the wavelength of 263 nm and two emissions in the ultraviolet and visible regions with the wavelengths of 263 nm and 372 nm were observed in the absorption spectrum of nanofibers without and with the extract, respectively. examination of the antibacterial properties in the present study confirmed that upon increasing the amount of the extract in the sample, the antibacterial effect of the electrospun nanofibers would be intensified in exposure to both Escherichia coli and Staphylococcus aureus.

Injectable hydrogels that mimic heart tissues can be considered a promissing perspective towards the future developments of cardiac tissue engineering. This study aims to fabricate an injectable, thermosensitive hydrogel consisting of chitosan/gelatin/glycerol phosphate. Due to their unique electro-conductivity characteristic, hydrogels can provide a suitable environment to accelerate cardiac cell proliferation. Polyaniline/multi-walled carboxylated carbon nanotube (PAni/c-MWNT) was prepared using Sodium Dodecyl Sulfate (SDS) emulsion. To prevent the interaction between the PAni/c-MWNT nanocomposite and hydrogel, the nanocomposite was coated with gelatin to form polyaniline/carboxylated carbon nanotube/gelatin (PAni/c-MWNT/G). The PAni/c-MWNT/G nanocomposite was then dispersed to provide electrical signals throughout the hydrogel. The gelation time, gel temperature, and mechanical properties of the hydrogel were measured using a rheometer. FTIR spectroscopy results revealed that the interaction between the aniline and c-MWNT/G could change the position of the quinone and benzene peaks. The conductivity of hydrogel-containing nanocomposite was found to be higher than that of c-MWNT and PAni. Scanning Electron Microscopy (SEM) confirmed the uniform distribution of PAni/c-MWNT/G nanocomposite throughout the hydrogel. The degradation rate of conductive hydrogel is lower than that of pure hydrogel. The MTT assay test showed the biocompatibility of the cell-hydrogel. Finally, Mesenchymal Stem Cells (MSCs) were cultured in the hydrogels for 14 days. Cell adhesion, cell viability, and proliferation were also examined. This study utilized PAni/c-MWNT/G, for the first time, to enhance the electro-conductivity of chitosan/gelatin/glycerol phosphate hydrogel. This conductive thermosensitive injectable hydrogel can be used to regenerate cardiac tissue and other electroactive tissues.

In the present study, gelatin/chitosan/zinc oxide hydrogels were prepared through solvent casting method in combination with lyophilization. In addition, the effects of adding 1.5 wt % zinc oxide nanoparticles on the microstructural and physico-chemical characteristics of genipin-crosslinked scaffolds were evaluated. The porosity of the newly formed hydrogels increased from about 93 up to 94 % (P < 0.05). Images taken by a Scanning Electron Microscope (SEM) illustrates the formation of a porous microstructure of distinct interconnected holes with an average size of 200 microns. Water absorption capacity of nanocomposite hydrogels at room temperature and 37 °C decreased from 1043 to 988 and 1206 to 1040 %, respectively; however, a significant increase in their initial swelling rate was observed. Upon adding nanoparticles, the in vitro degradation of scaffolds occurred faster than usual. According to the findings of this research, gelatin/chitosan/zinc oxide hydrogels which is characterized by favorable microstructural characteristics (i.e., uniform distribution of interconnected pores) and high initial swelling rate can be used as a potential substrate in the field of tissue engineering.

One of the most important problems of using magnesium alloys is their high corrosion rate. In order to solve this problem, the method of surface modification and coating has been considered. The main purpose of this research is to apply polycaprolactone/chitosan-1% Baghdadite polymer membrane by immersion method on anodized magnesium-aluminum AZ91 alloy in order to improve the corrosion resistance, biodegradability and biocompatibility of this alloy. The results of the electrochemical test show the improvement of the electrochemical resistance and the reduction of the electrochemical current density (10^3 times reduction) of the anodized magnesium-aluminum alloy AZ91 due to the application of the polymer-ceramic membrane. Also, the application of polymer-ceramic membrane has led to an increase in the surface roughness from 0.329 ± 0.02 (magnesium-aluminum AZ91) to 7.792 ± 0.34 micrometers. In order to evaluate the ability of apatite formation on the samples, the body simulating liquid test (phosphate buffer) was used. The results show that the formation of apatite layer on the surface of the sample can be considered as a measure of biodegradability

Magnetic nanoparticles are of interest in various research fields such as magnetic fluids, catalysts, biotechnology, medicine, information storage, and environmental issues. However, spinel ferrite magnetic nanoparticles with proper magnetic properties could not be used alone in these applications because of their lack of biocompatibility and instability in aqueous solutions. Surface coating is an effective strategy to eliminate or minimize this issue. In this study, FeFe2O4 and ZnFe2O4 spinel ferrites were synthesized using the reverse co-precipitation method under a nitrogen gas atmosphere. The magnetic behavior of the particles, determined by a vibrating magnetometer (VSM) showed the saturation magnet (Ms) values of the FeFe2O4 and ZnFe2O4 spinel. Fourier-transform infrared (FTIR)  spectra showed two high-frequency bands v1 and v2 at about 554-578 and 368-397 cm-1, respectively, which were related to the spinel structure. Finally, the synthesized FeFe2O4 nanoparticles were coated with chitosan and polyethylene glycol (PEG) biopolymers. The TEM and FTIR analysis indicated that the magnetic nanoparticles were uniformly coated by the biopolymers.

In this study, chitosan composite nanofibers containing tannic acid and zinc-based metal-organic framework (ZIF-8) were produced for application as a hemostatic wound dressing. First, metal-organic framework named zeolite imidazolate framework (ZIF-8) was synthesized and chitosan composite nanofibers containing tannic acid and ZIF-8 were fabricated through electrospinning. The effect of tannic acid and metal-organic framework on the morphology and hemostatic properties of chitosan nanofibers was studied. Scanning electron microscopy, X-ray diffraction and blood coagulation tests were utilized. The study of the morphology of nanofibrous wound dressings shows the fabrication of uniform and bead-free nanofibers with an average diameter of 120 to 150 nm. The addition of tannic acid, due to the formation of hydrogen bonds and increasing the viscosity of the polymer solution, increased the diameter of chitosan nanofibers. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests, which check the performance of extrinsic and intrinsic pathway of blood coagulation, respectively, were used to evaluate the hemostatic activity of the fabricated wound dressings. The results show that the fabricated nanofibrous wound dressings significantly affect the extrinsic pathway of blood coagulation and factor VII, so that the blood coagulation time is reduced by 60% compared to the control sample. Due to the suitable structural and morphological properties of fabricated composite nanofibers, as well as their accelerated coagulation performance, they can be used as a suitable candidate in wound dressing applications.